/**
* INTERNAL: Execute the query. If there are cached results return those. This must override the
* super to support result caching.
*
* @param session - the session in which the receiver will be executed.
* @return An object or vector, the result of executing the query.
* @exception DatabaseException - an error has occurred on the database
*/
public Object execute(AbstractSession session, AbstractRecord row) throws DatabaseException {
if (shouldCacheQueryResults()) {
if (getContainerPolicy().overridesRead()) {
throw QueryException.cannotCacheCursorResultsOnQuery(this);
}
if (shouldConformResultsInUnitOfWork()) {
throw QueryException.cannotConformAndCacheQueryResults(this);
}
if (isPrepared()) { // only prepared queries can have cached results.
Object queryResults = getQueryResults(session, row, true);
if (queryResults != null) {
if (QueryMonitor.shouldMonitor()) {
QueryMonitor.incrementReadAllHits(this);
}
// bug6138532 - check for "cached no results" (InvalidObject singleton) in query
// results, and return an empty container instance as configured
if (queryResults == InvalidObject.instance) {
return getContainerPolicy().containerInstance(0);
}
Collection results = (Collection) queryResults;
if (session.isUnitOfWork()) {
ContainerPolicy policy = getContainerPolicy();
Object resultCollection = policy.containerInstance(results.size());
Object iterator = policy.iteratorFor(results);
while (policy.hasNext(iterator)) {
Object result =
((UnitOfWorkImpl) session)
.registerExistingObject(policy.next(iterator, session), this.descriptor);
policy.addInto(result, resultCollection, session);
}
return resultCollection;
}
return results;
}
}
}
if (QueryMonitor.shouldMonitor()) {
QueryMonitor.incrementReadAllMisses(this);
}
return super.execute(session, row);
}
/**
* INTERNAL: All objects queried via a UnitOfWork get registered here. If the query went to the
* database.
*
* <p>Involves registering the query result individually and in totality, and hence refreshing /
* conforming is done here.
*
* @param result may be collection (read all) or an object (read one), or even a cursor. If in
* transaction the shared cache will be bypassed, meaning the result may not be originals from
* the parent but raw database rows.
* @param unitOfWork the unitOfWork the result is being registered in.
* @param arguments the original arguments/parameters passed to the query execution. Used by
* conforming
* @param buildDirectlyFromRows If in transaction must construct a registered result from raw
* database rows.
* @return the final (conformed, refreshed, wrapped) UnitOfWork query result
*/
public Object registerResultInUnitOfWork(
Object result,
UnitOfWorkImpl unitOfWork,
AbstractRecord arguments,
boolean buildDirectlyFromRows) {
// For bug 2612366: Conforming results in UOW extremely slow.
// Replacing results with registered versions in the UOW is a part of
// conforming and is now done while conforming to maximize performance.
if (shouldConformResultsInUnitOfWork()
|| this.descriptor.shouldAlwaysConformResultsInUnitOfWork()) {
return conformResult(result, unitOfWork, arguments, buildDirectlyFromRows);
}
// When building directly from rows, one of the performance benefits
// is that we no longer have to wrap and then unwrap the originals.
// result is just a vector, not a collection of wrapped originals.
// Also for cursors the initial connection is automatically registered.
if (buildDirectlyFromRows) {
List<AbstractRecord> rows = (List<AbstractRecord>) result;
ContainerPolicy cp = getContainerPolicy();
int size = rows.size();
Object clones = cp.containerInstance(size);
for (int index = 0; index < size; index++) {
AbstractRecord row = rows.get(index);
// null is placed in the row collection for 1-m joining to filter duplicate rows.
if (row != null) {
Object clone = buildObject(row);
cp.addInto(clone, clones, unitOfWork, row, this);
}
}
return clones;
}
ContainerPolicy cp;
Cursor cursor = null;
// If the query is redirected then the collection returned might no longer
// correspond to the original container policy. CR#2342-S.M.
if (getRedirector() != null) {
cp = ContainerPolicy.buildPolicyFor(result.getClass());
} else {
cp = getContainerPolicy();
}
// In the case of cursors just register the initially read collection.
if (cp.isCursorPolicy()) {
cursor = (Cursor) result;
// In nested UnitOfWork session might have been session of the parent.
cursor.setSession(unitOfWork);
cp = ContainerPolicy.buildPolicyFor(ClassConstants.Vector_class);
result = cursor.getObjectCollection();
}
Object clones = cp.containerInstance(cp.sizeFor(result));
AbstractSession sessionToUse = unitOfWork.getParent();
for (Object iter = cp.iteratorFor(result); cp.hasNext(iter); ) {
Object object = cp.next(iter, sessionToUse);
Object clone = registerIndividualResult(object, unitOfWork, this.joinedAttributeManager);
cp.addInto(clone, clones, unitOfWork);
}
if (cursor != null) {
cursor.setObjectCollection((Vector) clones);
return cursor;
} else {
return clones;
}
}
/** INTERNAL: Conform the result if specified. */
protected Object conformResult(
Object result,
UnitOfWorkImpl unitOfWork,
AbstractRecord arguments,
boolean buildDirectlyFromRows) {
if (getSelectionCriteria() != null) {
ExpressionBuilder builder = getSelectionCriteria().getBuilder();
builder.setSession(unitOfWork.getRootSession(null));
builder.setQueryClass(getReferenceClass());
}
// If the query is redirected then the collection returned might no longer
// correspond to the original container policy. CR#2342-S.M.
ContainerPolicy cp;
if (getRedirector() != null) {
cp = ContainerPolicy.buildPolicyFor(result.getClass());
} else {
cp = getContainerPolicy();
}
// This code is now a great deal different... For one, registration is done
// as part of conforming. Also, this should only be called if one actually
// is conforming.
// First scan the UnitOfWork for conforming instances.
// This will walk through the entire cache of registered objects.
// Let p be objects from result not in the cache.
// Let c be objects from cache.
// Presently p intersect c = empty set, but later p subset c.
// By checking cache now doesConform will be called p fewer times.
Map indexedInterimResult =
unitOfWork.scanForConformingInstances(
getSelectionCriteria(), getReferenceClass(), arguments, this);
Cursor cursor = null;
// In the case of cursors just conform/register the initially read collection.
if (cp.isCursorPolicy()) {
cursor = (Cursor) result;
cp = ContainerPolicy.buildPolicyFor(ClassConstants.Vector_class);
// In nested UnitOfWork session might have been session of the parent.
cursor.setSession(unitOfWork);
result = cursor.getObjectCollection();
// for later incremental conforming...
cursor.setInitiallyConformingIndex(indexedInterimResult);
cursor.setSelectionCriteriaClone(getSelectionCriteria());
cursor.setTranslationRow(arguments);
}
// Now conform the result from the database.
// Remove any deleted or changed objects that no longer conform.
// Deletes will only work for simple queries, queries with or's or anyof's may not return
// correct results when untriggered indirection is in the model.
Vector fromDatabase = null;
// When building directly from rows, one of the performance benefits
// is that we no longer have to wrap and then unwrap the originals.
// result is just a vector, not a container of wrapped originals.
if (buildDirectlyFromRows) {
Vector rows = (Vector) result;
fromDatabase = new Vector(rows.size());
for (int i = 0; i < rows.size(); i++) {
Object object = rows.elementAt(i);
// null is placed in the row collection for 1-m joining to filter duplicate rows.
if (object != null) {
Object clone =
conformIndividualResult(
object,
unitOfWork,
arguments,
getSelectionCriteria(),
indexedInterimResult,
buildDirectlyFromRows);
if (clone != null) {
fromDatabase.addElement(clone);
}
}
}
} else {
fromDatabase = new Vector(cp.sizeFor(result));
AbstractSession sessionToUse = unitOfWork.getParent();
for (Object iter = cp.iteratorFor(result); cp.hasNext(iter); ) {
Object object = cp.next(iter, sessionToUse);
Object clone =
conformIndividualResult(
object,
unitOfWork,
arguments,
getSelectionCriteria(),
indexedInterimResult,
buildDirectlyFromRows);
if (clone != null) {
fromDatabase.addElement(clone);
}
}
}
// Now add the unwrapped conforming instances into an appropriate container.
// Wrapping is done automatically.
// Make sure a vector of exactly the right size is returned.
Object conformedResult =
cp.containerInstance(indexedInterimResult.size() + fromDatabase.size());
Object eachClone;
for (Iterator enumtr = indexedInterimResult.values().iterator(); enumtr.hasNext(); ) {
eachClone = enumtr.next();
cp.addInto(eachClone, conformedResult, unitOfWork);
}
for (Enumeration enumtr = fromDatabase.elements(); enumtr.hasMoreElements(); ) {
eachClone = enumtr.nextElement();
cp.addInto(eachClone, conformedResult, unitOfWork);
}
if (cursor != null) {
cursor.setObjectCollection((Vector) conformedResult);
// For nested UOW must copy all in object collection to
// initiallyConformingIndex, as some of these could have been from
// the parent UnitOfWork.
if (unitOfWork.isNestedUnitOfWork()) {
for (Enumeration enumtr = cursor.getObjectCollection().elements();
enumtr.hasMoreElements(); ) {
Object clone = enumtr.nextElement();
indexedInterimResult.put(clone, clone);
}
}
return cursor;
} else {
return conformedResult;
}
}